Subsurface drainage was introduced in the Midwestern United States in the 1830s and has since become a necessity to sustain crop production in the region’s poorly drained soils. Is there any farmer in this region who does not understand the benefits of drainage? “Twenty Benefits of Drainage” was published in 1982 by OSU Drainage Extension Agricultural Engineer, Mel Palmer. The list goes beyond the improved trafficability and crop yield benefits. Most of those benefits still hold true 40 years later!
Despite its numerous benefits, some of the adverse impacts of drainage on the environment have become a major concern in recent decades. Two noteworthy water quality issues are caused by nitrogen and phosphorus, which can escape farm fields through drain tile: the formation of harmful (sometimes toxic) algal blooms in the Western Basin of Lake Erie and other lakes, and the huge hypoxic “dead zone” where the Mississippi River empties into the Gulf of Mexico. Note that agricultural drainage is not the only source of the nutrients reaching these water bodies, but it s one of the major contributors.
Conservation drainage: It is possible to minimize the negative impacts of drainage on the environment. The Golden Rule of Drainage is: “Drain only what is necessary for good crop growth and trafficability, and not one drop more.” “Conservation drainage” goes further, incorporating approaches and practices to minimize the environmental impacts on the downstream environment and ecology. Controlled drainage (drainage water management), drainage water recycling, saturated buffers, denitrifying bioreactors, phosphorus filters, and two-stage ditch design are some of the examples of conservation drainage. It is important to note that conservation drainage refers to in-field, edge-of-field, as well as ditch and stream-level conservation practices, as these are all important spatial units of agricultural drainage systems. More details on the conservation drainage practices can be found at tranformingdrainage.org and conservationdrainage.net.
OSU-Lima Branch Campus Agricultural Runoff Treatment System Project
Project Number: ALLENSWCD-FDFARM22
Grant Award: $650,000.00
Watershed: Lost Creek (041000070305)
Location: 40°44’37”, -84°01’38”; 2.7 miles east of Interstate 75 on Harding Highway
Project Description:
The Ohio State University’s Lima Branch Campus has farmland consisting of rented crop fields surrounding the campus that drain to the Lost Creek HUC12 watershed, a headwater area of the Maumee River Watershed (see the maps of fields below). This agricultural runoff water retention project will convert some portions of cropland into floodplain, wetlands and water retention that will be used to retain and passively treat runoff before recycling back onto the fielded for the purpose of irrigating crops. Additionally, OSU proposes to monitor the hydrology and water quality of these systems by installing needed weirs and flumes and sampling equipment. The following are the specific proposed conceptual practices.
Runoff and drainage water capture, retention, and use to provide irrigation water to fields 7 and 27. This project will develop floodplain access by converting low-producing areas near the channel via berm/dike installation and/or excavation. It will also develop a water retention and treatment wetland, with irrigation equipment for cropland runoff re-use (with electrical service). The farming enterprise has agreed to allow this low yielding production field 4 to be utilized for the floodplain access and the agricultural runoff treatment and retention with a forebay (to assist in future maintenance and longevity), a wetland, and a pump “vault”. Access for maintenance, and irrigation equipment (to recycle/irrigated runoff back onto growing crops) will be installed. This aspect of the project (recycling agricultural runoff) corresponds to producer concerns regarding changes in climate and timing of rainfall for production and provides positive trade-off for taking land out of production. Utilizing runoff through irrigation is a new and direct means of reducing nutrients by applying the captured water and nutrient load during the period that crops are most in need of moisture and nutrients. Approximately 3-4 acres will be converted to floodplain retention. An estimated 40 acres of acres of row crop runoff will be captured, treated and/or reused in a combination of wetland, retention and buffer that will comprise approximately 5 acres.
Status: ON-GOING CONSTRUCTION
Contractor: VTF Excavation LLC
Expected Completion: August 31, 2024
Saturated Buffer on OSU-Lima Field 17: A saturated buffer system was installed in August 16, 2022 to treat and reduce discharge of the drainage tile from field 17. Saturated buffers collect subsurface drainage water using a drainage control structure and divert it to a drainpipe that typically runs parallel to the stream receiving tile discharge under a vegetated buffer. These often substantially reduce the amount of water directly discharging and reduces nutrients carried in subsurface discharge providing denitrification and phosphorus reduction. They require little maintenance and do not negatively affect crop yields. This system will treat approximately 12 acres of cropland drainage water treated through the new saturated buffer.
Status: COMPLETED IN AUGUST 2022
For more info visit: https://www.allenswcd.com/osu-ag-run-off-treatment-system/